In fact, that 90% understates things. It is 90% of the 20% who were consistent Sanders supporters from March 2015 until April 2016.

So we have a core of "Never Hillary" who are not going to be persuaded. That's fine. They have their reasons and I am not going to try to persuade them otherwise. But from a productive standpoint, Dems (and anti-Trumps voting for Hillary) would get much more bang for the buck focusing on getting out the vote, keeping the left wing that has come into the fold happy, and avoiding pitched fights with Never Hillarys wherever possible.